The NMSSM Solution to the Fine-Tuning Problem, Precision Electroweak Constraints and the Largest LEP Higgs Event Excess

We present an extended study of how the Next to Minimal Supersymmetric Model easily avoids fine-tuning in electroweak symmetry breaking for a SM-like light Higgs with mass in the vicinity of 100\gev, as beautifully consistent with precision electroweak data, while escaping LEP constraints due to the dominance of $h\to aa$ decays with $m_a<2m_b$ so that a\to \tauptaum or jets. The residual $\sim 10$ branching ratio for h\to b\anti b explains perfectly the well-known LEP excess at \mh\sim 100\gev. Details of model parameter correlations and requirements are discussed as a function $\tan(\beta)$. Comparisons of fine-tuning in the NMSSM to that in the MSSM are presented. We also discuss fine-tuning associated with scenarios in which the $a$ is essentially pure singlet, has mass m_a>30\gev, and decays primarily to \gam\gam leading to an h\to aa\to 4\gam Higgs signal.Comment: 26 pages, 37 figures, published version with minor text and reference improvement

On the D0D^0 -- DsD_s lifetime difference and τ→7π+ντ\tau\to 7\pi + \nu_\tau decays

In this paper we discuss some aspects of inclusive decays of charmed mesons and also decays of the $\tau$ lepton into $\nu_\tau + 7\pi$. We find that phase space effects are likely to explain the observed lifetime ratio $\tau(D_s^+) / \tau(D^0)$ = 1.17. In particular one need not appeal to a large annihilation contribution in the inclusive $D^0$ decay which, being absent in $D_s^+$ decays could also contribute to the enhanced $D^0$ decay rate relative to that of the $D_s^+$. Examining a separate problem, we find that the rate for $\tau\to \nu_\tau + 7\pi$ is almost completely dominated by the tiny phase space for the final eight particle state. Using an effective chiral Lagrangian to estimate the matrix element yields a branching ratio into the channel of interest far smaller than the present upper bound.Comment: No figure

The Interplay Between Collider Searches For Supersymmetric Higgs Bosons and Direct Dark Matter Experiments

In this article, we explore the interplay between searches for supersymmetric particles and Higgs bosons at hadron colliders (the Tevatron and the LHC) and direct dark matter searches (such as CDMS, ZEPLIN, XENON, EDELWEISS, CRESST, WARP and others). We focus on collider searches for heavy MSSM Higgs bosons ($A$, $H$, $H^{\pm}$) and how the prospects for these searches are impacted by direct dark matter limits and vice versa. We find that the prospects of these two experimental programs are highly interrelated. A positive detection of $A$, $H$ or $H^{\pm}$ at the Tevatron would dramatically enhance the prospects for a near future direct discovery of neutralino dark matter. Similarly, a positive direct detection of neutralino dark matter would enhance the prospects of discovering heavy MSSM Higgs bosons at the Tevatron or the LHC. Combining the information obtained from both types of experimental searches will enable us to learn more about the nature of supersymmetry.Comment: 22 pages, 28 figure

Cabibbo-suppressed non-leptonic B- and D-decays involving tensor mesons

The Cabibbo-suppressed non-leptonic decays of B (and D) mesons to final states involving tensor mesons are computed using the non-relativistic quark model of Isgur-Scora-Grinstein-Wise with the factorization hypothesis. We find that some of these B decay modes, as B --> (K^*, D^*)D^*_2, can have branching ratios as large as 6 x 10^{-5} which seems to be at the reach of future B factories.Comment: Latex, 11 pages, to appear in Phys. Rev.

Puzzles of excited charm meson masses

We attempt a comprehensive analysis of the low lying charm meson states which present several puzzles, including the poor determination of masses of several non-strange excited mesons. We use the well-determined masses of the ground states and the strange first excited states to `predict' the mass of the non-strange first excited state in the framework of heavy hadron chiral perturbation theory, an approach that is complementary to the well-known analysis of Mehen and Springer. This approach points to values for the masses of these states that are smaller than the experimental determinations. We provide a critical assessment of these mass measurements and point out the need for new experimental information.Comment: 9 pages, 1 figure, accepted for publication in Physics Letters

A Heavy-Light Chiral Quark Model

We present a new chiral quark model for mesons involving a heavy and a light (anti-) quark. The model relates various combinations of a quark - meson coupling constant and loop integrals to physical quantities. Then, some quantities may be predicted and some used as input. The extension from other similar models is that the present model includes the lowest order gluon condensate of the order (300 MeV)^4 determined by the mass splitting of the 0^- and the 1^- heavy meson states. Within the model, we find a reasonable description of parameters such as the decay constants f_B and f_D, the Isgur-Wise function and the axial vector coupling g_A in chiral perturbation theory for light and heavy mesons.Comment: 31 pages, 13 figures, RevTex4.

D*-->Dpi and D*-->Dgamma decays: Axial coupling and Magnetic moment of D* meson

The axial coupling and the magnetic moment of D*-meson or, more specifically, the couplings g(D*Dpi) and g(D*Dgamma), encode the non-perturbative QCD effects describing the decays D*-->Dpi and D*-->Dgamma. We compute these quantities by means of lattice QCD with Nf=2 dynamical quarks, by employing the Wilson ("clover") action. On our finer lattice (a=0.065 fm) we obtain: g(D*Dpi)=20 +/- 2, and g(D0*D0gamma)=[2.0 +/- 0.6]/GeV. This is the first determination of g(D0*D0gamma) on the lattice. We also provide a short phenomenological discussion and the comparison of our result with experiment and with the results quoted in the literature.Comment: 22 pages, 3 figure